''Merivirus'' is a genus of

viruses A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are found in almo ...

that is the sole genus in the family ''Corticoviridae''. Meriviruses are

bacteriophage A bacteriophage (), also known informally as a phage (), is a virus that infects and replicates within bacteria. The term is derived . Bacteriophages are composed of proteins that Capsid, encapsulate a DNA or RNA genome, and may have structu ...

s; that is, their natural

hosts A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County * Host Island, in the Wilhelm Archipelago, Antarctica People * ...

are

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

. The genus contains two species. From 1981 to 2024, the genus was named ''Corticovirus'', sharing a name with its family.

Prophage A prophage is a bacteriophage (often shortened to "phage") genome that is integrated into the circular bacterial chromosome or exists as an extrachromosomal plasmid within the bacterial cell (biology), cell. Integration of prophages into the bacte ...

s closely related to bacteriophage PM2 are abundant in the genomes of aquatic bacteria, suggesting that the ecological importance of meriviruses might be underestimated. Bacteriophage PM2 was first described in 1968 after isolation from

seawater Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximat ...

sampled from the coast of

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

Taxonomy

The genus contains the following species: * ''Merivirus Cr39582'' * ''Merivirus PM2''

Virology

The virons consist of a round,

icosahedral In geometry, an icosahedron ( or ) is a polyhedron with 20 faces. The name comes . The plural can be either "icosahedra" () or "icosahedrons". There are infinitely many non- similar shapes of icosahedra, some of them being more symmetrical tha ...

, non-enveloped

capsid A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or m ...

of a diameter of 60 nm and an internal

lipid Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing ...

membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. Bi ...

located between outer and inner

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

shell. The shells are composed of three layers whose surfaces reveals a pattern with distinctive features, including bush-like spikes protruding from the twelve vertices. The icosahedral capsid (T = 21) is 56

nanometer 330px, Different lengths as in respect to the Molecule">molecular scale. The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm), or nanometer (American spelling Despite the va ...

s (nm) in diameter and is composed of 1200 P1 (spike) and 60 P2 (capsid) proteins. The pentameric receptor-binding spikes protrude from the 12 fivefold axes. The capsid encloses an internal lipid core containing the structural proteins P3 to P9.

Genome

The genome is not segmented, constitutes 13% of the virus's weight and contains a single molecule of circular,

supercoiled DNA supercoiling refers to the amount of twist in a particular DNA strand, which determines the amount of strain on it. A given strand may be "positively supercoiled" or "negatively supercoiled" (more or less tightly wound). The amount of a st ...

, double-stranded

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

of 10 kilo bases in length. The genome has a g + c content of 43%. It encodes 21 proteins. The genome is organised into three operons. Replication of the genome is via a rolling-circle mechanism, initiated by the virus encoded endonuclease P12.

Life cycle

Viral replication is cytoplasmic. Entry into the host cell is achieved by adsorption to the host cell surface followed by fusion of the viral membrane with the outer membrane of the host cell and subsequent genome delivery into the cell interior. DNA-templated transcription is the method of transcription. Bacteria of the genera ''

Pseudoalteromonas ''Pseudoalteromonas'' is a genus of marine bacteria. In 1995, Gauthier ''et al'' proposed ''Pseudoalteromonas'' as a new genus to be split from ''Alteromonas''. The ''Pseudoalteromonas'' species that were described before 1995 were originally par ...

'', '' Marinomonas'' and ''

Vibrio ''Vibrio'' is a genus of Gram-negative bacteria, which have a characteristic curved-rod (comma) shape, several species of which can cause foodborne infection or soft-tissue infection called Vibriosis. Infection is commonly associated with eati ...

'' serve as the natural host. Bacteriophage PM2 is a lytic virus and at the end of the infection cycle disrupts the host cell using a unique lysis system consisting of phage-encoded proteins P17 and P18 as well as an unidentified host autolysin. However, identification of PM2-like proviruses in bacterial genomes indicates that other members of this family might be temperate viruses. Transmission routes are passive diffusion.

References

External links

ICTV Online(10th) Report: Corticoviridae

{{Taxonbar, from=Q1135608 Bacteriophages Virus genera